Clearance and beyond: the complementary roles of GFR measurement and injury biomarkers in acute kidney injury (AKI)

Clinical validation of the novel fluorescent glomerular filtration rate tracer agent relmapirazin (MB-102)

The fluorescent compound relmapirazin has been rationally designed for use in point-of-care measurement of glomerular filtration rate (GFR), with attributes including negligible protein binding, negligible metabolites in vivo, negligible tubular secretion, and excellent chemical and photo stability. Twenty-four nonclinical assays were performed in accordance with FDA requirements yielding negligible toxicology concerns. Here, a clinical study was performed to validate relmapirazin as a GFR tracer in patients by comparison to iohexol. This was evaluated in 120 adults at three clinical sites with eGFR values ranging from normal to Stage 4 chronic kidney disease. Relmapirazin and iohexol were administered intravenously in consecutive boluses to each subject and serial blood samples obtained over the subsequent 12 hours. Plasma concentrations were measured and the corresponding plasma GFR for each agent was determined using a standard two-compartment pharmacokinetic assessment. Urine from each subject was collected for the entire 12-hour study period to measure the amount of administered dose appearing in the urine. A near perfect linear regression correlation was observed between the GFRs measured by these two tracers (r2=0.99). Bland-Altman analysis confirmed agreement between these two measures of GFR (limits of agreement -7.0 to +5.6 mL/min; mean of -0.7 mL/min). The GFR determined by relmapirazin was independent of GFR stratification by chronic kidney disease stage, and importantly by race. The percent of the administered relmapirazin dose recovered in the urine was greater than or equal to that of iohexol with no reported severe adverse events. Thus, relmapirazin may be used as a GFR tracer agent in humans.

Early Detection of Chronic Kidney Disease Using Plasma Neutrophil Gelatinase-Associated Lipocalin and Kidney Injury Molecule-1 in Small-Breed Dogs: A Retrospective Pilot Study

Multiple diagnostic modalities are urgently needed to identify early-stage kidney diseases. Various molecules have been investigated; however, most studies have focused on identifying specific biomarkers in urine. Considering that assessing the symmetrical dimethylarginine (SDMA) plasma concentration is more suitable as an early diagnostic test for chronic kidney disease (CKD) in routine veterinary practice, we aimed to investigate the clinical usefulness of plasma neutrophil gelatinase-associated lipocalin (pNGAL) and plasma kidney injury molecule-1 (pKIM-1) concentrations for CKD detection in small-breed dogs. Through a retrospective analysis, we found that numerous clinicopathological data showed a log-normal distribution, even when they satisfied normality tests. Moreover, the log-transformed pNGAL and pKIM-1 concentrations successfully identified CKD International Renal Interest Society (IRIS) stages 1-4 and the risk group with underlying CKD risk factors. Correlation analysis and group comparison of other factors confirmed the possibility of using these two biomarkers for detecting the CKD risk group and IRIS stage 1. Receiver operating characteristic curve analysis revealed that the diagnostic accuracy for discriminating the risk group was superior in the order of pKIM-1, pNGAL, SDMA, and serum creatinine levels. In conclusion, these results suggest that pKIM-1 and pNGAL are possible early or quantifiable markers of insignificant CKD or can be at least used as an adjunct with traditional indicators.

Comparative analysis of two-hour creatinine clearance and the C-G formula for renal function assessment in critically ill patients

Objective and rationale

To investigate if the 2-h creatinine clearance (Ccr2) provides a more precise and timely assessment of renal function in critically ill patients compared to the Cockcroft-Gault formula (CrC-G).

Materials and methods

This cohort study incorporated 74 patients who were hospitalized for more than 48 h in the Intensive Care Unit over 6 months. A 24-h urine collection protocol was observed, and concurrently, 316 2-h urine specimens were obtained. Then calculated and analyzed the correlation and consistency between Ccr2, CrC-G, and 24-h creatinine clearance (Ccr24) values. The rates of change in Ccr2(ΔCcr2) and CrC-G(ΔCrC-G) were compared over two consecutive samples.

Results

The R-values of Ccr2 and Ccr24 in the early, middle and late 24 h were 0.640, 0.886 and 0.854 (P < 0.001), with biases of -2.1, 1.7, and 6.3 ml/min/1.73 m2, respectively. Meanwhile, the R-values for CrC-G and Ccr24 at these time points were 0.618, 0.822, and 0.828(P < 0.001), with biases of -14.0, -5.2, and -1.8 ml/min/1.73 m2, respectively. For patients with Ccr24≥60 ml/min/1.73 m2, the R-value of Ccr2 and Ccr24 during the middle 2 h was 0.852(P < 0.001), while the R-values for CrC-G and Ccr24 were 0.763(P < 0.001), with biases of -2.3 ml/min/1.73 m2 and -14.2 ml/min/1.73 m2 respectively. For the group with Ccr24 ≥ 120 ml/min/1.73 m2 (n = 72), both Ccr2 and Ccr24 displayed a statistically significant elevation compared to CrC-G (P < 0.001), yet no significant difference was observed between Ccr2 and Ccr24 (P = 0.289). Out of 50 patients, 46(92 %) experienced a ΔCcr2≥20 % at least once, compared to 20(40 %) with a ΔCrC-G≥20 %(P < 0.001). 25(50 %) with a ΔCcr2≥50 %, compared to 3(6 %) with a ΔCrC-G≥50 %(P < 0.001).

Conclusion

Ccr2 demonstrates a more accurate and more timely indicator of renal function in critically ill patients than CrC-G.

Point-of-Care Serum Proenkephalin as an Early Predictor of Mortality in Patients Presenting to the Emergency Department with Septic Shock

BACKGROUND

The aim of the present study is to investigate the prognostic utility of point-of-care (POC)-measured proenkephalin (PENK), a novel biomarker, in terms of predicting in-hospital mortality in patients presenting to the emergency department (ED) with septic shock.

METHODS

Bedside PENK was measured in consecutive patients presenting to the ED with septic shock according to the Sepsis-3 clinical criteria. The association of PENK with inflammatory and routine biomarkers, and its role as a predictor of in-hospital mortality, was examined.

RESULTS

Sixty-one patients with septic shock [53% females, median age 83 years (IQR 71-88)] were evaluated. Median (IQR) values of creatinine, plasma lactate, soluble urokinase plasminogen activator receptor (SuPAR), procalcitonin and PENK were 1.7 (1.0-2.9) mg/dL, 3.6 (2.1-6.8) mmol/L, 13.1 (10.0-21.4) ng/mL, 2.06 (0.84-3.49) ng/mL, and 205 (129-425) pmol/L, respectively. LogPENK significantly correlated with LogLactate (rho = 0.369, p = 0.004), LogCreatinine (rho = 0.537, p < 0.001), LogProcalcitonin (rho = 0.557, p < 0.001), and LogSuPAR (rho = 0.327, p = 0.011). During hospitalization, 39/61 (64%) patients died. In a multivariable logistic regression model, logPENK was an independent predictor of in-hospital mortality (OR 11.9, 95% CI: 1.7-84.6, p = 0.013).

CONCLUSION

POC PENK levels measured upon presentation to the ED strongly correlated with metabolic, renal and inflammatory biomarkers, and may serve as a predictor of in-hospital mortality in patients with septic shock.

Indexed neutrophil gelatinase associated lipocalin: a novel biomarker for the assessment of acute kidney injury

INTRODUCTION

Acute kidney injury (AKI) is a clinically relevant and common complication among patients with acute coronary syndrome. Neutrophil gelatinase-associated lipocalin (NGAL), secreted from different cells including renal tubules, has been widely studied as an early marker for kidney injury. However, chronic kidney disease (CKD) could impact NGAL levels and alter their predictive performance. Some studies attempted to address this issue by setting different cutoff values for patients with CKD, with limited success to date. Our aim was to evaluate a novel estimated glomerular filtration rate (eGFR)-adjusted "indexed NGAL" and its ability to predict in-hospital AKI among patients with ST elevation myocardial infarction.

METHODS

We performed a prospective, observational, single center study involving patients with ST elevation myocardial infarction admitted to the coronary intensive care unit. Serum samples for baseline NGAL were collected within 24 h following hospital admission. The eGFR was calculated using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation. In-hospital AKI was determined as occurring after ≥ 24 h from admission. To perform an individualized adjustment, we used the result of 24 h NGAL divided by the eGFR measured upon admission to the hospital (Indexed-NGAL; I-NGAL).

RESULTS

Our cohort includes 311 patients, of whom 123 (40%) had CKD, and 66 (21%) suffered in-hospital AKI. NGAL levels as well as I-NGAL levels were significantly higher in patients with AKI (136 vs. 86, p < 0.01 and 3.13 VS. 1.06, p < 0.01, respectively). Multivariate analysis revealed I-NGAL to be independently associated with AKI (OR 1.34 (1.10-1.58), p < 0.01). I-NGAL had a higher predictive ability than simple NGAL results (AUC-ROC of 0.858 vs. 0.778, p < 0.001).

CONCLUSION

Adjusting NGAL values according to eGFR yields a new indexed NGAL value that enables better prediction of AKI regardless of baseline kidney function.

Oleoylethanolamide attenuates acute-to-chronic kidney injury: in vivo and in vitro evidence of PPAR-α involvement

Chronic kidney disease (CKD) development after acute kidney injury (AKI) involves multiple mechanisms, including inflammation, epithelial-mesenchymal transition (EMT), and extracellular matrix deposition, leading to progressive tubulointerstitial fibrosis. Recently, a central role for peroxisome-proliferator activated receptor (PPAR)-α has been addressed in preserving kidney function during AKI. Among endogenous lipid mediators, oleoylethanolamide (OEA), a PPAR-α agonist, has been studied for its metabolic and anti-inflammatory effects. Here, we have investigated OEA effects on folic acid (FA)-induced kidney injury in mice and the underlying mechanisms. OEA improved kidney function, normalized urine output, and reduced serum BUN, creatinine, and albuminuria. Moreover, OEA attenuated tubular epithelial injury, as shown by histological analysis, and decreased expression of neutrophil gelatinase-associated lipocalin and kidney injury molecule-1. Gene expression analysis of kidney tissue indicated that OEA limited immune cell infiltration and inflammation. Moreover, OEA significantly inhibited Wnt7b and Catnb1 gene transcription and α-smooth muscle actin expression, indicating suppression of EMT. Accordingly, OEA exhibited an anti-fibrotic effect, as shown by Masson staining and the reduced levels of transforming growth factor (TGF)-β1, fibronectin, and collagen IV. Mechanistically, the nephroprotective effect of OEA was related to PPAR-α activation since OEA failed to exert its beneficial activity in FA-insulted PPAR-α-/- mice. PPAR-α involvement was also confirmed in HK2 cells where GW6471, a PPAR-α antagonist, blunted OEA activity on the TGF-β1 signalling pathway and associated pro-inflammatory and fibrotic patterns. Our findings revealed that OEA counteracts kidney injury by controlling inflammation and fibrosis, making it an effective therapeutic tool for limiting AKI to CKD progression.

Interaction between anemia and renal dysfunction in relation to long-term survival following acute myocardial infarction

BACKGROUND

Anemia and chronic kidney disease (CKD) adversely affect prognosis following acute myocardial infarction (AMI). We aimed to assess their interaction regarding long-term survival post-AMI.

METHODS

This is a single-center, retrospective analysis of consecutive AMI survivors. Stratified by admission-time anemia status and CKD grade, as determined by hemoglobin and creatinine levels, the cohort was evaluated for all-cause mortality at 10 years after hospital discharge.

RESULTS

A total of 11,395 patients (69.1% males, mean age 65.8 ± 13.9 years, 49.6% with ST elevation MI) were included, of whom 29.9% had anemia and 15.9% - grade 3b or higher CKD. CKD was more advanced among anemic patients and the prevalence of anemia rose as CKD grade increased (p for trend < 0.001). At 10 years, 47.8% of patients died. Notwithstanding differences in baseline characteristics, presentation, and treatment between those with various anemia status and CKD grades, anemia presence (HR 1.40, 95% CI 1.32-1.49, p < 0.001) and increasing CKD grade (HR 1.10, 95% CI 1.02-1.20, p for trend < 0.001) were independently associated with a higher mortality risk. The incremental hazard imposed by either anemia or more advanced CKD was limited to patients with normal renal function and up to grade 3a (in the total cohort and the conservative treatment subgroup) or 4 (in the invasive revascularization subgroup) CKD. The added risk associated with increasing CKD grade also affected non-anemic individuals irrespective of the specific CKD grade.

CONCLUSION

Anemia and more advanced CKD are associated with reduced long-term survival post-AMI, inflicting higher risk when conjoined in lower-grade CKD.

Kidney functional reserve and damage biomarkers in subclinical chronic kidney disease and acute kidney injury

Significant loss of kidney function is not easily identified by serum creatinine (sCr)-based measurements. In the presence of normal sCr, decreased kidney functional reserve (KFR) may identify a significant loss of function. We evaluated KFR in experimental subclinical chronic kidney disease (sCKD) before and after brief ischemia-reperfusion injury (IRI). Using fluorescein isothiocyanate-labeled sinistrin, glomerular filtration rate (GFR) was measured transcutaneously before and after adenine-induced sCKD, and 1 and 2 wk after brief IRI, and compared with urinary kidney damage biomarkers. sCKD reduced stimulated and unstimulated GFR by ∼20% while reducing KFR by 50%. IRI reduced unstimulated GFR for 14 days, but KFR remained relatively unchanged in sCKD and transiently increased in control kidneys at 7 days. sCr increased and creatinine clearance (CrCl) decreased only immediately after IRI; sCr and CrCl correlated poorly with measured GFR except on day 1 after IRI. Heterogeneity in sCr and CrCl resulted from variation in tubular creatinine secretion. The increase in damage biomarker concentrations persisted for up to 14 days after IRI, allowing retrospective detection of sCKD before AKI by urine clusterin/urine kidney injury molecule-1 with an area under the curve of 1.0. sCr and CrCl are unreliable unless sCr is acutely elevated. Measurement of KFR and urine damage biomarker excretion detected sCKD despite normal sCr and CrCl. After IRI, the urine clusterin-to-urine kidney injury molecule-1 ratio may identify prior sCKD.NEW & NOTEWORTHY Early kidney function loss is poorly identified by serum creatinine (sCr)-based measurements. Direct kidney functional reserve (KFR) measurement before kidney injury and elevated urinary biomarkers clusterin and kidney injury molecule-1 detect subclinical chronic kidney disease (sCKD) after kidney injury despite normal range sCr and creatinine clearance. Reliance on sCr masks underlying sCKD. Acute kidney injury risk evaluation requires direct glomerular filtration rate measurement and KFR, whereas kidney damage biomarkers facilitate identification of prior subclinical injury.

Significant perioperative parameters affecting postoperative complications within 30 days following craniotomy for primary malignant brain tumors

BACKGROUND

The occurrence of postoperative complications within 30 days (PC1M) of a craniotomy for the removal of a primary malignant brain tumor has been associated with a poor prognosis. However, it is still unclear to early predict the occurrence of PC1M. This study aimed to identify the potential perioperative predictors of PC1M from its preoperative, intraoperative, and 24-h postoperative parameters.

METHODS

Patients who had undergone craniotomy for primary malignant brain tumor (World Health Organization grades III and IV) from January 2011 to December 2020 were enrolled from a databank of Kaohsiung Veterans General Hospital, Taiwan. The patients were classified into PC1M and nonPC1M groups. PC1M was defined according to the classification by Landriel et al. as any deviation from an uneventful 30-day postoperative course. In both groups, data regarding the baseline characteristics and perioperative parameters of the patients, including a new marker-kinetic estimated glomerular filtration rate, were collected. Logistic regression was used to analyze the predictability of the perioperative parameters.

RESULTS

The PC1M group included 41 of 95 patients. An American Society of Anesthesiologists score of > 2 (aOR, 3.17; 95% confidence interval [CI], 1.19-8.45; p = 0.021), longer anesthesia duration (aOR, 1.16; 95% CI, 0.69-0.88; p < 0.001), 24-h postoperative change in hematocrit by >  - 4.8% (aOR, 3.45; 95% CI, 1.22-9.73; p = 0.0019), and 24-h postoperative change in kinetic estimated glomerular filtration rate of < 0 mL/min (aOR, 3.99; 95% CI, 1.52-10.53; p = 0.005) were identified as independent risk factors for PC1M via stepwise logistic regression analysis. When stratified according to the age of ≥ 65 years (OR, 11.55; 95% CI, 1.30-102.79; p = 0.028), the reduction of kinetic estimated glomerular filtration rate was more robustly associated with a higher risk of PC1M.

CONCLUSIONS

Four parameters were demonstrated to significantly influence the risk of PC1M in patients undergoing primary malignant brain tumor removal. Measuring and verifying these markers, especially kinetic estimated glomerular filtration rate, would help early recognition of PC1M risk in clinical care.

The predictive value of [TIMP-2]*[IGFBP7] in adverse outcomes for acute kidney injury: a systematic review and meta-analysis

MATERIALS AND METHODS

Relevant articles published up to 17 June 2023 were retrieved from five databases (Cochrane Library/Embase/PubMed/SinoMed/Web of Science). The pre-established inclusion and exclusion criteria determined the selection of publications. Pooled sensitivity (SEN), specificity (SPE), diagnostic odds ratio, likelihood ratio, and summary receiver operating characteristic curve were employed to assess the predictive value. The presence or potential sources of heterogeneity were investigated via subgroup and SEN analyses.

RESULTS

Ten published and eligible studies (1559 cases) were included in the evaluation for the capability of [TIMP-2]*[IGFBP7] to predict the poor prognosis of AKI through the random effect model. Pooled SEN, SPE, diagnostic odds ratio, and positive and negative likelihood ratios were 0.82 (95% CI: 0.77-0.86, I2 = 53.4%), 0.64 (95% CI: 0.61-0.67, I2 = 88.3%), 14.06 (95% CI: 7.31-27.05, I2 = 55.0%), 2.859 (95% CI: 2.15-3.77, I2 = 80.7%), and 0.28 (95% CI: 0.20-0.40, I2 = 35.0%), respectively. The estimated area under the curve was 0.8864 (standard error: 0.0306), and the Q* was 0.7970 (standard error: 0.0299). The endpoints and cutoff values were the main causes of heterogeneity.

CONCLUSIONS

[TIMP-2]*[IGFBP7] is possible in predicting poor prognosis of AKI, but it is better to be applied along with other indicators or clinical risk factors.

Adsorption and Clearance of the Novel Fluorescent Tracer Agent MB-102 During Continuous Renal Replacement Therapy: In Vitro Results

MB-102 is a novel fluorescent tracer agent that is exclusively removed from the body by glomerular filtration. This agent can be detected transdermally to provide a real-time measurement of glomerular filtration rate at the point-of-care and is currently in clinical studies for such. MB-102 clearance during continuous renal replacement therapy (CRRT) is unknown. Its plasma protein binding (~0%), molecular weight (~372 Da) and volume of distribution (15-20 L) suggest that it may be removed by renal replacement therapies. To determine the disposition of MB-102 during CRRT, an in vitro study assessing the transmembrane clearance (CL TM ) and adsorptive clearance of MB-102 was conducted. A validated in vitro bovine blood continuous hemofiltration (HF) and continuous hemodialysis (HD) models were performed using two types of hemodiafilters to evaluate CL TM of MB-102. For HF, three different ultrafiltration rates were evaluated. For HD, four different dialysate flow rates were evaluated. Urea was used as a control. No MB-102 adsorption to the CRRT apparatus or either of hemodiafilters was observed. MB-102 is readily removed by HF and HD. Dialysate and ultrafiltrate flow rates directly influence MB-102 CLTM. Hence MB-102 CLTM should be measurable for critically ill patients receiving CRRT.

Diagnostic and Prognostic Roles of C-Reactive Protein, Procalcitonin, and Presepsin in Acute Kidney Injury Patients Initiating Continuous Renal Replacement Therapy

For reducing the high mortality rate of severe acute kidney injury (AKI) patients initiating continuous renal replacement therapy (CRRT), diagnosing sepsis and predicting prognosis are essential. However, with reduced renal function, biomarkers for diagnosing sepsis and predicting prognosis are unclear. This study aimed to assess whether C-reactive protein (CRP), procalcitonin, and presepsin could be used to diagnose sepsis and predict mortality in patients with impaired renal function initiating CRRT. This was a single-center, retrospective study involving 127 patients who initiated CRRT. Patients were divided into sepsis and non-sepsis groups according to the SEPSIS-3 criteria. Of the 127 patients, 90 were in the sepsis group and 37 were in the non-sepsis group. Cox regression analysis was performed to determine the association between the biomarkers (CRP, procalcitonin, and presepsin) and survival. CRP and procalcitonin were superior to presepsin for diagnosing sepsis. Presepsin was closely related to the estimated glomerular filtration rate (eGFR) (r = -0.251, p = 0.004). These biomarkers were also evaluated as prognostic markers. Procalcitonin levels ≥3 ng/mL and CRP levels ≥31 mg/L were associated with higher all-cause mortality using Kaplan-Meier curve analysis. (log-rank test p = 0.017 and p = 0.014, respectively). In addition, procalcitonin levels ≥3 ng/mL and CRP levels ≥31 mg/L were associated with higher mortality in univariate Cox proportional hazards model analysis. In conclusion, a higher lactic acid, sequential organ failure assessment score, eGFR, and a lower albumin level have prognostic value to predict mortality in patients with sepsis initiating CRRT. Moreover, among these biomarkers, procalcitonin and CRP are significant factors for predicting the survival of AKI patients with sepsis-initiating CRRT.

Diagnosing acute kidney injury ahead of time in critically ill septic patients using kinetic estimated glomerular filtration rate

INTRODUCTION

Accurate and actionable diagnosis of Acute Kidney Injury (AKI) ahead of time is important to prevent or mitigate renal insufficiency. The purpose of this study was to evaluate the performance of Kinetic estimated Glomerular Filtration Rate (KeGFR) in timely predicting AKI in critically ill septic patients.

METHODS

We conducted a retrospective analysis on septic ICU patients who developed AKI in AmsterdamUMCdb, the first freely available European ICU database. The reference standard for AKI was the Kidney Disease: Improving Global Outcomes (KDIGO) classification based on serum creatinine and urine output (UO). Prediction of AKI was based on stages defined by KeGFR and UO. Classifications were compared by length of ICU stay (LOS), need for renal replacement therapy and 28-day mortality. Predictive performance and time between prediction and diagnosis were calculated.

RESULTS

Of 2492 patients in the cohort, 1560 (62.0%) were diagnosed with AKI by KDIGO and 1706 (68.5%) by KeGFR criteria. Disease stages had agreement of kappa = 0.77, with KeGFR sensitivity 93.2%, specificity 73.0% and accuracy 85.7%. Median time to recognition of AKI Stage 1 was 13.2 h faster for KeGFR, and 7.5 h and 5.0 h for Stages 2 and 3. Outcomes revealed a slight difference in LOS and 28-day mortality for Stage 1.

CONCLUSIONS

Predictive performance of KeGFR combined with UO criteria for diagnosing AKI is excellent. Compared to KDIGO, deterioration of renal function was identified earlier, most prominently for lower stages of AKI. This may shift the actionable window for preventing and mitigating renal insufficiency.

Definitions, phenotypes, and subphenotypes in acute kidney injury-Moving towards precision medicine

The current definition of acute kidney injury (AKI) is generic and, based only on markers of function, is unsuitable for guiding individualized treatment. AKI is a complex syndrome with multiple presentations and causes. Targeted AKI management will only be possible if different phenotypes and subphenotypes of AKI are recognised, based on causation and related pathophysiology. Molecular signatures to identify subphenotypes are being recognised, as specific biomarkers reveal activated pathways. Assessment of individual clinical risk needs wider dissemination to allow identification of patients at high risk of AKI. New and more timely markers for glomerular filtration rate (GFR) are available. However, AKI diagnosis and classification should not be limited to GFR, but include tubular function and damage. Combining damage and stress biomarkers with functional markers enhances risk prediction, and identifies a population enriched for clinical trials targeting AKI. We review novel developments and aim to encourage implementation of these new techniques into clinical practice as a strategy for individualizing AKI treatment akin to a precision medicine-based approach.

Protective effect of Cistanche deserticola on gentamicin-induced nephrotoxicity in rats

Objective

Gentamicin (GM) is a commonly used aminoglycoside antibiotic, however, renal toxicity has limited its usage. The present study was designed to evaluate the ameliorative effect of Cistanche deserticola on GM-induced nephrotoxicity in rats.

Methods

The nephrotoxicity in rats was induced by intraperitoneal administration of GM (100 mg/kg) for 10 consecutive days. Glomerular filtration rate, blood urea nitrogen, creatinine and kidney histopathology were detected to assess the GM-induced nephrotoxicity. The oxidative stress (catalase, superoxide dismutase, glutathione and malondialdehyde) was assessed. The inflammatory response (tumor necrosis factor-α, interleukin-6, myeloperoxidase and nuclear factor-kappa B) and apoptotic marker (Bax and Bcl-2) were also evaluated.

Results

The results showed that water and 75% ethanol extracts of C. deserticola (named CDW and CDE, respectively) (100, 200 and 400 mg/kg) in combination with GM could recover the reduction of glomerular filtration rate and enhance the renal endogenous antioxidant capability induced by GM. The increase in the expression of renal inflammatory cytokines (tumor necrosis factor-α and interleukin-6), nuclear protein of nuclear factor-kappa B (p65) and the activity of myeloperoxidase induced by GM was significantly decreased upon CDW or CDE treatment. In addition, CDW or CDE treatment could decrease the Bax protein expression and increase the Bcl-2 protein expression in GM-induced nephrotoxicity in rats significantly.

Conclusion

The study demonstrated that C. deserticola treatment could attenuate kidney dysfunction and structural damage in rats induced by GM through the reduction of inflammation, oxidative stress and apoptosis.

Acute Changes in Serum Creatinine and Kinetic Glomerular Filtration Rate Estimation in Early Phase of Acute Pancreatitis

In patients with acutely changing kidney function, equations used to estimate glomerular filtration rate (eGFR) must be adjusted for dynamic changes in the concentrations of filtration markers (kinetic eGFR, KeGFR). The aim of our study was to evaluate serum creatinine-based KeGFR in patients in the early phase of acute pancreatitis (AP) as a marker of changing renal function and as a predictor of AP severity. We retrospectively calculated KeGFR on day 2 and 3 of the hospital stay in a group of 147 adult patients admitted within 24 h from the onset of AP symptoms and treated in two secondary-care hospitals. In 34 (23%) patients, changes in serum creatinine during days 1-3 of the hospital stay exceeded 26.5 µmol/L; KeGFR values almost completely differentiated those with increasing and decreasing serum creatinine (area under receiver operating characteristic curve, AUROC: 0.990 on day 3). In twelve (8%) patients, renal failure was diagnosed during the first three days of the hospital stay according to the modified Marshall scoring system, which was associated with significantly lower KeGFR values. KeGFR offered good diagnostic accuracy for renal failure (area under receiver operating characteristic-AUROC: 0.942 and 0.950 on days 2 and 3). Fourteen (10%) patients developed severe AP. KeGFR enabled prediction of severe AP with moderate diagnostic accuracy (AUROC: 0.788 and 0.769 on days 2 and 3), independently of age, sex, comorbidities and study center. Lower KeGFR values were significantly associated with mortality. Significant dynamic changes in renal function are common in the early phase of AP. KeGFR may be useful in the assessment of kidney function in AP and the prediction of AP severity.

Early reduction of estimated Glomerular Filtration Rate (eGFR) predicts poor outcome in acutely ill hospitalized COVID-19 patients firstly admitted to medical regular wards (eGFR-COV19 study)

Background

Methods

Results

Conclusions

Advances in the study of subclinical AKI biomarkers

Acute kidney injury (AKI) is a prevalent and serious illness in all clinical departments, with a high morbidity and death rate, particularly in intensive care units, where prevention and treatment are crucial. As a result, active prevention, early detection, and timely intervention for acute kidney injury are critical. The current diagnostic criteria for acute kidney injury are an increase in serum creatinine concentration and/or a decrease in urine output, although creatinine and urine output merely reflect changes in kidney function, and AKI suggests injury or damage, but not necessarily dysfunction. The human kidney plays a crucial functional reserve role, and dysfunction is only visible when more than half of the renal mass is impaired. Tubular damage markers can be used to detect AKI before filtration function is lost, and new biomarkers have shown a new subset of AKI patients known as "subclinical AKI." Furthermore, creatinine and urine volume are only marginally effective for detecting subclinical AKI. As a result, the search for new biomarkers not only identifies deterioration of renal function but also allows for the early detection of structural kidney damage. Several biomarkers have been identified and validated. This study discusses some of the most promising novel biomarkers of AKI, including CysC, NGAL, KIM-1, lL-18, L-FABP, IGFBP7, TIMP-2, Clusterin, and Penkid. We examine their performance in the diagnosis of subclinical AKI, limitations, and future clinical practice directions.

Evaluation of Developmental and Reproductive Toxicity in Rabbits for MB-102, a Fluorescent Tracer Agent Designed for Real-Time Measurement of Glomerular Filtration Rate

The fluorescent tracer, MB-102, has been designed for the direct, real-time measurement of glomerular filtration rate. Previous studies, both in vitro and in vivo (rats, rabbits and dogs), were conducted to assess potential toxicity including single dose toxicity, mutation assay, chromosomal aberration assay, phototoxicity, local tolerance study, micronuclease assay, hERG channel changes, CNS and cardiovascular safety. The results of these studies led to a safety/toxicology profile for this agent deemed sufficient by the FDA to conduct Phase I and Phase II human clinical studies. In this paper we report on maternal toxicity and the potential effects on embryo-fetal development and the toxicokinetics of MB-102 administered daily via intravenous (bolus) injection into pregnant rabbits during the period of organogenesis gestation day 7-19. Assessment of toxicity was based on mortality, clinical observations, body weight, food consumption, reproductive performance and necropsy and cesarean section findings. Blood samples were collected for toxicokinetic evaluation. No test article findings were noted in any of these studies. The only clinical findings observed were the discoloration of skin, eyes or pelage in the 2 higher dose groups, which were considered related to the color and fluorescent properties of MB-102 and were deemed non-adverse. Exposure, as assessed by C_max and AUC_(0-6) increased in a dose dependent manner from 4.5 to 113 mg/kg/day. No accumulation of the test article was noted after multiple doses were administered. Thus, intravenous administration of MB-102 was not associated with any adverse developmental or reproductive toxicities in pregnant rabbits.

Clinical Phenotyping of Out-of-Hospital Cardiac Arrest Patients With Shockable Rhythm - Machine Learning-Based Unsupervised Cluster Analysis

BACKGROUND

The hypothesis of this study is that latent class analysis could identify the subphenotypes of out-of-hospital cardiac arrest (OHCA) patients associated with the outcomes and allow us to explore heterogeneity in the effects of extracorporeal cardiopulmonary resuscitation (ECPR).

METHODS AND RESULTS

This study was a retrospective analysis of a multicenter prospective observational study (CRITICAL study) of OHCA patients. It included adult OHCA patients with initial shockable rhythm. Patients from 2012 to 2016 (development dataset) were included in the latent class analysis, and those from 2017 (validation dataset) were included for evaluation. The association between subphenotypes and outcomes was investigated. Further, the heterogeneity of the association between ECPR implementation and outcomes was explored. In the study results, a total of 920 patients were included for latent class analysis. Three subphenotypes (Groups 1, 2, and 3) were identified, mainly characterized by the distribution of partial pressure of O2(PO2), partial pressure of CO2(PCO2) value of blood gas assessment, cardiac rhythm on hospital arrival, and estimated glomerular filtration rate. The 30-day survival outcomes were varied across the groups: 15.7% in Group 1; 30.7% in Group 2; and 85.9% in Group 3. Further, the association between ECPR and 30-day survival outcomes by subphenotype groups in the development dataset was as varied. These results were validated using the validation dataset.

CONCLUSIONS

The latent class analysis identified 3 subphenotypes with different survival outcomes and potential heterogeneity in the effects of ECPR.

The Urinary Level of Injury Biomarkers Is Not Univocally Reflective of the Extent of Toxic Renal Tubular Injury in Rats

Nephrotoxicity is a major cause of intrinsic acute kidney injury (AKI). Because renal tissue damage may occur independently of a reduction in glomerular filtration rate and of elevations in plasma creatinine concentration, so-called injury biomarkers have been proposed to form part of diagnostic criteria as reflective of tubular damage independently of renal function status. We studied whether the urinary level of NGAL, KIM-1, GM2AP, t-gelsolin, and REGIIIb informed on the extent of tubular damage in rat models of nephrotoxicity, regardless of the etiology, moment of observation, and underlying pathophysiology. At a time of overt AKI, urinary biomarkers were measured by Western blot or ELISA, and tubular necrosis was scored from histological specimens stained with hematoxylin and eosin. Correlation and regression studies revealed that only weak relations existed between biomarkers and tubular damage. Due to high interindividual variability in the extent of damage for any given biomarker level, urinary injury biomarkers did not necessarily reflect the extent of the underlying tissue injury in individual rats. We contended, in this work, that further pathophysiological contextualization is necessary to understand the diagnostic significance of injury biomarkers before they can be used for renal tubular damage severity stratification in the context of nephrotoxic and, in general, intrinsic AKI.

Biomarker Rule-in or Rule-out in Patients With Acute Diseases for Validation of Acute Kidney Injury in the Emergency Department (BRAVA): A Multicenter Study Evaluating Urinary TIMP-2/IGFBP7

Background

Urine tissue inhibitor of metalloproteinases-2/insulin-like growth factor-binding protein 7 (TIMP-2/IGFBP7) (NephroCheck, Ortho Clinical Diagnostics, Raritan, NJ, USA) is a US Food and Drug Administration-approved biomarker for risk assessment of acute kidney injury (AKI) in critically ill adult patients in intensive care units; however, its clinical impact in the emergency department (ED) remains unproven. We evaluated the utility of NephroCheck for predicting AKI development and short-term mortality in the ED.

Methods

This was a prospective, observational, five-center international study. We consecutively enrolled ED patients admitted with ≥30% risk of AKI development (assessed by ED physician: ED score) or acute diseases. Serum creatinine was tested on ED arrival (T0), day 1, and day 2 (T48); urine for NephroCheck was collected at T0 and T48. We performed ROC curve and reclassification analyses.

Results

Among the 529 patients enrolled (213 females; median age, 65 years), AKI developed in 59 (11.2%) patients. The T0 NephroCheck value was higher in the AKI group than in the non-AKI group (median 0.77 vs. 0.29 (ng/m)2/1,000, P=0.001), and better predicted AKI development than the ED score (area under the curve [AUC], 0.64 vs. 0.53; P=0.04). In reclassification analyses, adding NephroCheck to the ED score improved the prediction of AKI development (P<0.05). The T0 NephroCheck value predicted 30-day mortality (AUC, 0.68; P<0.001).

Conclusions

NephroCheck can predict both AKI development and short-term mortality in at-risk ED patients. NephroCheck would be a useful biomarker for early ruling-in or ruling-out of AKI in the ED.

Identifying Candidate Protein Markers of Acute Kidney Injury in Acute Decompensated Heart Failure

One-quarter of patients with acute decompensated heart failure (ADHF) experience acute kidney injury (AKI)—an abrupt reduction or loss of kidney function associated with increased long-term mortality. There is a critical need to identify early and real-time markers of AKI in ADHF; however, to date, no protein biomarkers have exhibited sufficient diagnostic or prognostic performance for widespread clinical uptake. We aimed to identify novel protein biomarkers of AKI associated with ADHF by quantifying changes in protein abundance in the kidneys that occur during ADHF development and recovery in an ovine model. Relative quantitative protein profiling was performed using sequential window acquisition of all theoretical fragment ion spectra–mass spectrometry (SWATH–MS) in kidney cortices from control sheep (n = 5), sheep with established rapid-pacing-induced ADHF (n = 8), and sheep after ~4 weeks recovery from ADHF (n = 7). Of the 790 proteins quantified, we identified 17 candidate kidney injury markers in ADHF, 1 potential kidney marker of ADHF recovery, and 2 potential markers of long-term renal impairment (differential abundance between groups of 1.2–2.6-fold, adjusted p < 0.05). Among these 20 candidate protein markers of kidney injury were 6 candidates supported by existing evidence and 14 novel candidates not previously implicated in AKI. Proteins of differential abundance were enriched in pro-inflammatory signalling pathways: glycoprotein VI (activated during ADHF development; adjusted p < 0.01) and acute phase response (repressed during recovery from ADHF; adjusted p < 0.01). New biomarkers for the early detection of AKI in ADHF may help us to evaluate effective treatment strategies to prevent mortality and improve outcomes for patients.

Neutrophil Gelatinase-Associated Lipocalin Acts as a Robust Early Diagnostic Marker for Renal Replacement Therapy in Patients with Russell's Viper Bite-Induced Acute Kidney Injuries

Snakebite-induced acute kidney injury (AKI) is frequently observed in patients following bites from vipers such as Russell's viper (Daboia russelii) in India. Currently, the levels of serum creatinine are mainly used as a marker to determine the necessity for renal replacement therapy (RRT) (haemodialysis) in severe cases of AKI. However, it takes up to 48 h to ascertain a distinct change in creatinine levels compared to its baseline level upon admission. The time lost between admission and the 48 h timepoint significantly affects the clinical management of snakebite victims. Moreover, early diagnosis of AKI and decision on the necessity for RRT in snakebite victims is critical in saving lives, reducing long-term complications, and minimising treatment costs arising from expensive haemodialysis. Neutrophil gelatinase-associated lipocalin (NGAL) has been recently studied as a robust early marker for AKI in non-snakebite patients. However, its suitability for clinical use in snakebite victims has not been rigorously established. Here, we demonstrate the clinical significance of plasma NGAL as a robust marker for RRT following AKI using a large cohort (309) of Russell's viper victims without any pre-existing health conditions. NGAL levels upon admission are positively correlated with creatinine levels at 48 h in different stages of AKI. Overall, NGAL acts as a robust early marker to ascertain the need for RRT following Russell's viper bites. The quantification of NGAL can be recommended as a routine test in hospitals that treat snakebites to decide on RRT at early time points instead of waiting for 48 h to confirm the increase in creatinine levels. The diagnostic use of NGAL in Russell's viper victims with pre-existing comorbidities and for other vipers should be evaluated in future studies.

Circulating heart failure biomarkers beyond natriuretic peptides: review from the Biomarker Study Group of the Heart Failure Association (HFA), European Society of Cardiology (ESC)

New biomarkers are being evaluated for their ability to advance the management of patients with heart failure. Despite a large pool of interesting candidate biomarkers, besides natriuretic peptides virtually none have succeeded in being applied into the clinical setting. In this review, we examine the most promising emerging candidates for clinical assessment and management of patients with heart failure. We discuss high-sensitivity cardiac troponins (Tn), procalcitonin, novel kidney markers, soluble suppression of tumorigenicity 2 (sST2), galectin-3, growth differentiation factor-15 (GDF-15), cluster of differentiation 146 (CD146), neprilysin, adrenomedullin (ADM), and also discuss proteomics and genetic-based risk scores. We focused on guidance and assistance with daily clinical care decision-making. For each biomarker, analytical considerations are discussed, as well as performance regarding diagnosis and prognosis. Furthermore, we discuss potential implementation in clinical algorithms and in ongoing clinical trials.

The kinetic estimated glomerular filtration rate ratio predicts acute kidney injury

AIM

Kinetic estimated Glomerular Filtration Rate (KeGFR) approximates GFR under non-steady-state conditions. We investigated whether the ratio of KeGFR difference to baseline eGFR could predict acute kidney injury (AKI) earlier than a creatinine-based algorithm that triggered an AKI electronic Alert (eAlert).

METHODS

This retrospective, single-centre, proof-of-concept cohort study assessed all patients diagnosed with AKI by an automated serum creatinine-based eAlert. The kinetic eGFR, the kinetic eGFR difference from baseline and the ratio of difference to baseline was calculated in subjects with at least two serum creatinine (sCr) measurements within 72 h of AKI.

RESULTS

Patients in the AKI cohort (n = 140) had a significant decline in KeGFR ratio (AKI: 17% IQR 7% to 29%, Non-AKI: 0 IQR -12% to 9%; P-value <.0001). A decrease of the ratio greater than 10% predicted AKI with a sensitivity of 66%, a specificity of 77%, a positive predictive value of 63%, and negative predictive value of 80%. The median lead time between KeGFR ratio decrease and AKI was 24 h (IQR: 19-27 h).

CONCLUSIONS

KeGFR ratio is a cheap, simple method that predicted AKI 24 h before laboratory detection. KeGFR may facilitate triaging patients to increased monitoring or intervention.

Acute kidney injury

Acute kidney injury (AKI) is defined by a sudden loss of excretory kidney function. AKI is part of a range of conditions summarized as acute kidney diseases and disorders (AKD), in which slow deterioration of kidney function or persistent kidney dysfunction is associated with an irreversible loss of kidney cells and nephrons, which can lead to chronic kidney disease (CKD). New biomarkers to identify injury before function loss await clinical implementation. AKI and AKD are a global concern. In low-income and middle-income countries, infections and hypovolaemic shock are the predominant causes of AKI. In high-income countries, AKI mostly occurs in elderly patients who are in hospital, and is related to sepsis, drugs or invasive procedures. Infection and trauma-related AKI and AKD are frequent in all regions. The large spectrum of AKI implies diverse pathophysiological mechanisms. AKI management in critical care settings is challenging, including appropriate volume control, nephrotoxic drug management, and the timing and type of kidney support. Fluid and electrolyte management are essential. As AKI can be lethal, kidney replacement therapy is frequently required. AKI has a poor prognosis in critically ill patients. Long-term consequences of AKI and AKD include CKD and cardiovascular morbidity. Thus, prevention and early detection of AKI are essential.

Measured and Estimated Glomerular Filtration Rate in the ICU: A Prospective Study

OBJECTIVES

To compare estimated glomerular filtration rate using classical static and kinetic equations with measured glomerular filtration rate assessed by plasma iohexol clearance in a mixed population of critical care patients.

PATIENTS

Unselected patients older than 18 and admitted to a general ICU.

DESIGN

Interventional prospective single center study.

INTERVENTION

Measurement of glomerular filtration rate by the plasma clearance of an IV single dose of iohexol and estimation of glomerular filtration rate with creatinine or cystatin C-based standard and kinetic equations as well as urinary creatinine clearance.

MEASUREMENTS AND MAIN RESULTS

Sixty-three patients were included with a median age of 66 years old. The median measured glomerular filtration rate was 51 mL/min/1.73 m (interquartile range, 19-85 mL/min/1.73 m). All used equations displayed significant biases, high errors, and poor accuracy when compared with measured glomerular filtration rate, overestimating renal function. The highest accuracy and lowest error were observed with cystatin C-based chronic kidney disease epidemiology collaboration equations. Both modification of diet in renal disease and Cockcroft-Gault equations displayed the lowest performance. Kinetic models did not improve performances, except in patients with unstable creatinine levels. Creatinine- but not cystatin C-based estimations largely derived over ICU stay, which appeared more related to sarcopenia than fluid balance. Finally, estimated glomerular filtration rate misclassified patients according to classical glomerular filtration rate categories in approximately half of the studied cases.

CONCLUSIONS

All known estimated glomerular filtration rate equations displayed high biases and unacceptable errors when compared with measured glomerular filtration rate in a mixed ICU population, with the lowest performance related to creatinine-based equations compared with cystatin C. In the ICU, we advocate for caution when using creatinine based estimated glomerular filtration rate equations. Drifting of serum creatinine levels over time should also be taken into consideration when assessing renal function in the ICU.

Cystatin C kidney functional reserve: a simple method to predict outcome in chronic kidney disease

BACKGROUND

Kidney Functional Reserve (KFR), the only clinical kidney stress test, is not routinely measured because complexity of measurement has limited clinical application. We investigated the utility of plasma cystatin C (CysC) after oral protein loading to determine KFR in stage 3 and 4 CKD.

METHODS

Following a 24 hour low protein diet, KFR was measured after oral protein by hourly plasma CysC and compared with simultaneous creatinine clearance (CrCl) and radionuclide Tc-99m-DTPA (mGFR) measurement in an observational, single-centre cohort study of adults with CKD 3 and CKD 4. Subjects were followed for three years for fast (F) or slow (S) CKD progression, dialysis requirement or death or a combination of major adverse kidney events (MAKE-F or -S).

RESULT

CysC, CrCl and Tc-99m DPTA mGFR measurements of KFR in 19 CKD 3 and 21 CKD 4 patients yielded good agreement. KFR was not correlated with baseline kidney function. Eight CKD 3 (42%) and 11 CKD 4 (52%) subjects reached their lowest serum CysC concentration four hours after protein loading. CysC KFR and baseline serum creatinine (sCr) predicted (death or dialysis) or MAKE-F with respective AUC = 0.73 (95% CI: 0.48 to 0.89) and 0.71 (95% CI: 0.51 to 0.84). Including CysC KFR, age, baseline sCr and nadir CysC predicted a decrease in sCr-eGFR greater than 1.2 mL/min per year (MAKE-S) with AUC = 0.89.

CONCLUSIONS

Serial CysC avoided timed urine collection and radionuclide exposure and yielded equivalent estimates of KFR. Serial CysC may facilitate monitoring of KFR in clinical practice.

Detection of Renal Injury Following Primary Coronary Intervention among ST-Segment Elevation Myocardial Infarction Patients: Doubling the Incidence Using Neutrophil Gelatinase-Associated Lipocalin as a Renal Biomarker

Background: A subgroup of patients with acute kidney injury (AKI) do not fulfil the functional criteria for AKI diagnosis but show elevated levels of new biomarkers reflecting tubular injury, suggesting that these patients suffer “subclinical AKI”. We investigated the incidence and possible implications of “subclinical AKI”, compared to no and clinical AKI among ST elevation myocardial infarction patients (STEMI) treated with primary coronary intervention (PCI). Methods: We included 223 patients with STEMI treated with PCI. Neutrophil gelatinase-associated lipocalin (NGAL) was used as a marker of renal tubular damage in the absence of functional AKI, with NGAL levels ≥100 ng/mL suggesting subclinical AKI. Patients were assessed for the occurrence of in-hospital adverse outcomes. Results: Of the study patients, 45 (25%) had subclinical AKI. These patients were more likely to have left ventricular ejection fraction ≤45% (33% vs. 23%. p = 0.01), in-hospital adverse outcomes (73% vs. 48%; p = 0.005), and a combination of the two. The multivariate regression model demonstrated that subclinical AKI was independently associated with in-hospital adverse outcomes (OR 3.71, 95% CI 1.30–10.62, p = 0.02). Conclusions: Subclinical AKI is common among STEMI patients and is independently associated with adverse outcomes, even in the absence of functional AKI.

Urinary clusterin and cystatin B as biomarkers of tubular injury in dogs following envenomation by the European adder

Diagnosing acute kidney injury remains a challenge since the established renal biomarkers, serum creatinine (sCr) and symmetric dimethylarginine (SDMA) reflect glomerular function and not tubular injury. Sensitive tubular markers such as urinary clusterin (uClust) and cystatin B (uCysB) have been proposed to detect AKI at an earlier stage. Since envenomation by the European adder (Vipera berus berus) could serve as a spontaneous disease model of AKI we investigated these new biomarkers in affected dogs. Concentrations of uClust and uCysB as well as sCr and SDMA were analyzed retrospectively in stored samples from 26 dogs with snake envenomation and 13 healthy controls. Higher concentrations of uClust (P < 0.012) and uCysB (P < 0.001) were observed in the snake-envenomed group. Normalization of uClust and uCysB to urinary creatinine did not alter the results. No differences were observed in sCr and SDMA between the snake-envenomed group and the healthy control group. Spearman rank correlation analysis revealed a strong association of uClust with uCysB in the snake-envenomed dogs (r = 0.75 P < 0.001) but not in the healthy controls. The high percentage of snake-envenomed dogs with increased uClust and uCysB concentrations in the absence of increased sCr and SDMA suggests renal tubular injury in the affected dogs. Larger prospective case-controlled studies are warranted to evaluate the clinical utility and prognostic value of these biomarkers.

24-hour Serum Creatinine Variation Associates with Short- and Long-Term All-Cause Mortality: A Real-World Insight into Early Detection of Acute Kidney Injury

Real-world evidence describing the variation in serum creatinine (S-Cre) within 24 hours and its prognostic value is unknown. We enrolled 14 912 adults who received two S-Cre measurements within 24 hours at a tertiary hospital between 2003 and 2016. The study population was divided into four groups according to the hospital service settings where the baseline and second S-Cre were measured: Group 1, Outpatient-to-Outpatient; Group 2, Outpatient-to-ED (emergency department) or Inpatient; Group 3, ED-to-ED or Inpatient; and Group 4, Inpatient-to-Inpatient. The main predictors were the difference between the two S-Cre measurements (ΔS-Cre) and the percent change (ΔS-Cre%). The main outcomes were 30-day, 1-year, or 3-year all-cause mortality. A total of 6753 and 8159 patients with an increase and a decrease within-day ΔS-Cre, respectively. Among 6753 patients who had deteriorating ΔS-Cre or ΔS-Cre%, the adjusted hazard ratio (aHR) for 1-year all-cause mortality for each 0.1 mg/dL or 5% change in S-Cre was 1.09 (95% confidence interval [CI]: 1.07, 1.11) and 1.03 (95% CI: 1.03, 1.04). In 8159 patients with improving ΔS-Cre%, the aHR was 0.97 (95% CI: 0.94, 1.00). Groups 3 and 4 had statistically significant positive linear relationships between deteriorating ΔS-Cre% and 30-day and 3-year mortality. The optimal cut-offs for deteriorating ΔS-Cre% for predicting 30-day mortality were approximately 22% for Group 3 and 20% for Group 4. Inpatient within-day deteriorating ΔS-Cre or ΔS-Cre% above 0.2 mg/dL or 20%, respectively, is associated with all-cause mortality. Monitoring 24-hour S-Cre variation identifies acute kidney injury earlier than the conventional criteria.

Recent advances of biosensors for hypertension and nephrology

PURPOSE OF REVIEW

Hypertension (HTN) and chronic kidney disease (CKD) are significant problems. With recent advances in technologies, biosensors have shown a great potential to provide better home monitoring in hypertension (HTN), medication compliance, diagnostic device for kidney disease, CKD/end-stage renal disease (ESRD) care, and post kidney transplant management.

RECENT FINDINGS

Multiple devices/biosensors have been developed related to HTN, kidney function including real-time glomerular filtration rate, CKD/end-stage renal disease, and transplant care. In recent advances in wearable biosensors, point of care monitoring system could provide more integrated care to the patients via telenephrology.

SUMMARY

This review focuses on the recent advances in biosensors which may be useful for HTN and nephrology. We will discuss future potential clinical implication of these biosensors.

Potential hepatic and renal toxicity induced by the biflavonoids from Ginkgo biloba

Evidence continues to grow on potential health risks associated with Ginkgo biloba and its constituents. While biflavonoid is a subclass of the flavonoid family in Ginkgo biloba with a plenty of pharmacological properties, the potential toxicological effects of biflavonoids remains largely unknown. Thus, the aim of this study was to investigate the in vitro and in vivo toxicological effects of the biflavonoids from Ginkgo biloba (i.e., amentoflavone, sciadopitysin, ginkgetin, isoginkgetin, and bilobetin). In the in vitro cytotoxicity test, the five biflavonoids all reduced cell viability in a dose-dependent manner in human renal tubular epithelial cells (HK-2) and human normal hepatocytes (L-02), indicating they might have potential liver and kidney toxicity. In the in vivo experiments, after intragastrical administration of these biflavonoids at 20 mg·kg^-1·d^-1 for 7 days, serum biochemical analysis and histopathological examinations were performed. The activity of alkaline phosphatase was significantly increased after all the biflavonoid administrations and widespread hydropic degeneration of hepatocytes was observed in ginkgetin or bilobetin-treated mice. Moreover, the five biflavonoids all induced acute kidney injury in treated mice and the main pathological lesions were confirmed to the tubule, glomeruli, and interstitium injuries. As the in vitro and in vivo results suggested that these biflavonoids may be more toxic to the kidney than the liver, we further detected the mechanism of biflavonoids-induced nephrotoxicity. The increased TUNEL-positive cells were detected in kidney tissues of biflavonoids-treated mice, accompanied by elevated expression of proapoptotic protein BAX and unchanged levels of antiapoptotic protein BCL-2, indicating apoptosis was involved in biflavonoids-induced nephrotoxicity. Taken together, our results suggested that the five biflavonoids from Ginkgo biloba may have potential hepatic and renal toxicity and more attentions should be paid to ensure Ginkgo biloba preparations safety.

Emerging microRNA biomarkers for acute kidney injury in acute decompensated heart failure

Acute decompensated heart failure (ADHF) is associated with a high incidence of acute kidney injury (AKI), an abrupt loss of kidney function associated with a near doubling of mortality at 1 year. In addition to the direct threat acute HF itself poses to kidney function, the beneficial effects of commonly prescribed HF treatments must be weighed against their potentially adverse effects on glomerular perfusion. Consequently, there is an urgent need to identify early markers for AKI in ADHF to facilitate timely implementation of supportive measures to minimize kidney damage and improve outcomes. The recent recognition of the diagnostic potential of circulating microRNAs presents the potential to address this gap if microRNAs specific for AKI can be identified in serial plasma, serum and/or urine samples from well-phenotyped cohorts of ADHF patients, including a proportion with AKI. This review summarizes emerging circulating diagnostic and prognostic microRNA biomarkers (serum, plasma or urine) in HF and AKI.

Neutrophil Gelatinase-Associated Lipocalin as an Early Diagnostic Biomarker of Acute Kidney Injury in Snake Bite

Background:

Snakebite envenomation is a major public health problem in the developing world, and the effects of viper envenomation on renal tissues leading to acute kidney injury (AKI) are well known. However, the usefulness of neutrophil gelatinase-associated lipocalin (NGAL) as a biomarker to detect AKI in viper envenomation cases were not studied much.

Aims and Objectives:

The present study was undertaken to find out plasma NGAL levels and assess its usefulness among the hospitalized Viperidae group of snakebite victims in predicting acute kidney injury.

Materials and Methods:

The plasma NGAL level was estimated within 6–8 h of all the 184 cases of viper bites along with other laboratory parameters.

Results:

It was elevated much before the elevation of serum creatinine levels, irrespective of the age, gender, and bite to hospital time. The sensitivity and specificity was 99.37 and 96.15, respectively. Elevated plasma NGAL levels in viper bite helped not only to detect AKI early but also assisted to plan for appropriate intervention.

Conclusion:

It is suggested to include estimation of plasma NGAL in the point of care testing, especially in emergency settings handling snakebite cases. However, more studies are recommended to find out its serial levels in snakebite cases following different kinds of snake envenomation with different clinical and laboratory manifestations in different age groups and gender belonging to different population so as to arrive at valid conclusions.

The incidence, characteristics, outcomes and associations of small short-term point-of-care creatinine increases in critically ill patients

PURPOSE

We assessed the incidence, characteristics, outcomes and associations of small, short-term point-of-care creatinine increases in critically ill patients.

METHODS

We prospectively identified the first episode of small (>1 μmol/L/h) short-term (3-4 h) point-of-care creatinine increase between two sequential arterial blood gas measurements. We followed patients for the subsequent development of Kidney Disease: Improving Global Outcomes (KDIGO) defined acute kidney injury (AKI) in the intensive care unit (ICU).

RESULTS

Of 387 patients, 279 (72.1%) developed an episode of small short-term point-of-care creatinine increase and 212 (54.8%) developed AKI. Such episodes occurred at a median of 5 (IQR 2-10) hours after ICU admission, while AKI occurred at a median of 15 (IQR 9-28) hours after admission. Patients with such episodes were more likely to be mechanically ventilated on admission (83.9 vs. 44.4%; p < .001) and had higher hospital mortality (10.9 vs. 3.7%, p = .03). Creatinine increase episodes had a sensitivity of 86% (95% CI 78-95) and specificity of 31% (95% CI 26-36) for subsequent AKI stages 2 and 3 in 24 h.

CONCLUSIONS

Small, short-term point-of-care creatinine increase episodes are common. They are associated with illness severity, occur early, precede AKI by 10 h and are sensitive rather than specific markers of AKI.

Glomerular Filtration Rate Estimation by a Novel Numerical Binning-Less Isotonic Statistical Bivariate Numerical Modeling Method

Statistical bivariate numerical modeling is a method to infer an empirical relationship between unpaired sets of data based on statistical distributions matching. In the present paper, a novel efficient numerical algorithm is proposed to perform bivariate numerical modeling. The algorithm is then applied to correlate glomerular filtration rate to serum creatinine concentration. Glomerular filtration rate is adopted in clinical nephrology as an indicator of kidney function and is relevant for assessing progression of renal disease. As direct measurement of glomerular filtration rate is highly impractical, there is considerable interest in developing numerical algorithms to estimate glomerular filtration rate from parameters which are easier to obtain, such as demographic and `bedside’ assays data.

Subclinical AKI: ready for primetime in clinical practice?

There has been considerable progress over the last decade in the standardization of the acute kidney injury (AKI) definition with the publication of the RIFLE, AKIN, KDIGO and ERBP classification criteria. However, these classification criteria still rely on imperfect parameters such as serum creatinine and urinary output. The use of timed urine collections, kinetic eGFR (estimated glomerular filtration rate), real time measurement of GFR and direct measures of tubular damage can theoretically aid in a more timely diagnosis of AKI and improve patients' outcome. There has been an extensive search for new biomarkers indicative of structural tubular damage but it remains controversial whether these new markers should be included in the current classification criteria. The use of these markers has also led to the creation of a new concept called subclinical AKI, a condition where there is an increase in biomarkers but without clinical AKI, defined as an increase in serum creatinine and/or a decrease in urinary output. In this review we provide a framework on how to critical appraise biomarker research and on how to position the concept of subclinical AKI. The evaluation of biomarker performance and the usefulness of the concept 'subclinical AKI' requires careful consideration of the context these biomarkers are used in (clinical versus research setting) and the goal we want to achieve (risk assessment versus prediction versus early diagnosis versus prognostication). It remains currently unknown whether an increase in biomarkers levels without functional repercussion is clinically relevant and whether including biomarkers in classification criteria will improve patients' outcome.

Proenkephalin A 119-159 (Penkid) Is an Early Biomarker of Septic Acute Kidney Injury: The Kidney in Sepsis and Septic Shock (Kid-SSS) Study

Introduction

Sepsis is the leading cause of acute kidney injury (AKI) in critically ill patients. The Kidney in Sepsis and Septic Shock (Kid-SSS) study evaluated the value of proenkephalin A 119-159 (penkid)-a sensitive biomarker of glomerular function, drawn within 24 hours upon intensive care unit (ICU) admission and analyzed using a chemiluminescence immunoassay-for kidney events in sepsis and septic shock.

Methods

The Kid-SSS study was a substudy of Adrenomedullin and Outcome in Severe Sepsis and Septic Shock (AdrenOSS) (NCT02393781), a prospective, observational, multinational study including 583 patients admitted to the intensive care unit with sepsis or septic shock and a validation cohort of 525 patients from the French and euRopean Outcome reGistry in Intensive Care Units (FROG-ICU) study. The primary endpoint was major adverse kidney events (MAKEs) at day 7, composite of death, renal replacement therapy, and persistent renal dysfunction. The secondary endpoints included AKI, transient AKI, worsening renal function (WRF), and 28-day mortality.

Results

Median age was 66 years (interquartile range 55-75), and 28-day mortality was 22% (95% confidence interval [CI] 19%-25%). Of the patients, 293 (50.3%) were in shock upon ICU admission. Penkid was significantly elevated in patients with MAKEs, persistent AKI, and WRF (median = 65 [IQR = 45-106] vs. 179 [114-242]; 53 [39-70] vs. 133 [79-196] pmol/l; and 70 [47-121] vs. 174 [93-242] pmol/l, all P < 0.0001), also after adjustment for confounding factors (adjusted odds ratio = 3.3 [95% CI = 1.8-6.0], 3.9 [95% CI = 2.1-7.2], and 3.4 [95% CI = 1.9-6.2], all P < 0.0001). Penkid increase preceded elevation of serum creatinine with WRF and was low in renal recovery.

Conclusion

Admission penkid concentration was associated with MAKEs, AKI, and WRF in a timely manner in septic patients.

A critical review of adverse effects to the kidney: mechanisms, data sources, and in silico tools to assist prediction

INTRODUCTION

The kidney is a major target for toxicity elicited by pharmaceuticals and environmental pollutants. Standard testing which often does not investigate underlying mechanisms has proven not to be an adequate hazard assessment approach. As such, there is an opportunity for the application of computational approaches that utilize multiscale data based on the Adverse Outcome Pathway (AOP) paradigm, coupled with an understanding of the chemistry underpinning the molecular initiating event (MIE) to provide a deep understanding of how structural fragments of molecules relate to specific mechanisms of nephrotoxicity. Aims covered: The aim of this investigation was to review the current scientific landscape related to computational methods, including mechanistic data, AOPs, publicly available knowledge bases and current in silico models, for the assessment of pharmaceuticals and other chemicals with regard to their potential to elicit nephrotoxicity. A list of over 250 nephrotoxicants enriched with, where possible, mechanistic and AOP-derived understanding was compiled. Expert opinion: Whilst little mechanistic evidence has been translated into AOPs, this review identified a number of data sources of in vitro, in vivo, and human data that may assist in the development of in silico models which in turn may shed light on the interrelationships between nephrotoxicity mechanisms.

Predictive Value of Serum Creatinine, Blood Urea Nitrogen, Uric Acid, and β2-Microglobulin in the Evaluation of Acute Kidney Injury after Orthotopic Liver Transplantation

Background

As a major complication after orthotopic liver transplantation (OLT), the occurrence of acute kidney injury (AKI) is frequently defined by serum creatinine (Cr); however, the accuracy of commonly used blood urea nitrogen (BUN), uric acid (UA), and β₂-microglobulin (β₂-MG) remains to be explored. This retrospective study compared the accuracy of these parameters for post-OLT AKI evaluation.

Methods

Patients who underwent OLT in three centers between July 2003 and December 2013 were enrolled. The postoperative AKI group was diagnosed by the Kidney Disease Improving Global Outcomes (KDIGO) criteria and classified by stage. Measurement data were analyzed using the t-test or Wilcoxon rank-sum test; enumerated data were analyzed using the Chi-square test or Fisher's exact test. Diagnostic reliability and predictive accuracy were evaluated using receiver operating characteristic (ROC) curve analysis.

Results

This study excluded 976 cases and analyzed 697 patients (578 men and 119 women); the post-OLT AKI incidence was 0.409. Compared with the no-AKI group, the AKI group showed very significant differences in Model for End-stage Liver Disease score (14.74 ± 9.91 vs. 11.07 ± 9.54, Z = 5.404; P < 0.001), hepatic encephalopathy (45 [15.8%] vs. 30 [7.3%], χ² = 12.699; P < 0.001), hemofiltration (28 [9.8%] vs. 0 [0.0%], χ² = 42.171; P < 0.001), and 28-day mortality (23 [8.1%] vs. 9 [2.2%], χ² = 13.323; P <0.001). Moreover, mean values of Cr, BUN, UA, and β₂-MG in the AKI group differed significantly at postoperative days 1, 3, and 7 (all P < 0.001). ROC curve area was 0.847 of Cr for the detection of AKI Stage 1 (sensitivity 80.1%, specificity 75.7%, cutoff value 88.23 μmol/L), 0.916 for Stage 2 (sensitivity 87.6%, specificity 82.6%, cutoff value 99.9 μmol/L), and 0.972 for Stage 3 (sensitivity 94.1%, specificity 88.2%, cutoff value 122.90 μmol/L).

Conclusion

The sensitivity and specificity of serum Cr might be a high-value indicator for the diagnosis and grading of post-OLT AKI.